a) Field of the Invention
The present invention relates to an IC socket compatible with CSP (chip-sized package) or BGA (ball grid array) type IC packages, specifically to that preferably used for a burn-in test.
b) Description of the Related Art
For sockets for CSP or BGA type IC packages, various structures have been proposed (refer to Japanese Patent Preliminary Publication Nos. Hei 6-89764, Hei 6-203926, for example). In general. in a BGA type IC package, bumps which protrude from the lower surface of the package body are hemispherically or spherically shaped out of a low-melting-point metal such as a solder material. Therefore, when such an IC package is subjected to a heat-resistance test (125.degree. C.-150.degree. C.) or the like while being mounted on an IC socket, the solder balls, which are softened by heat, are deformed due to contact force between the solder balls and contact pins of the IC socket, to lose their coplanarlity, and thus would cause a problem when the package is mounted on a printed circuit board for practical use. It is required for an IC socket, other than to solve this problem, to effectively rub its contact pins against the solder balls of the IC package (i.e. to perform "wiping" operation) for assuring electrical connection with minimum contact resistance.